The present invention is directed to a fluid pressure sensor of the type constructed with a semiconductor diaphragm, and more particularly to such a sensor from which a temperature signal is also derived. Such an arrangement is particularly useful in automotive control systems.
In many control systems a plurality of different signal inputs are utilized to regulate some output function. By way of example in an automotive vehicle having a clutch for regulating transfer of drive torque to the vehicle drive wheels, the application and release of such a clutch can be controlled mechanically, or by fluid, such as air or oil under pressure. When a fluid under pressure is utilized for the application and release of the clutch, it is frequently desirable to monitor the clutch apply pressure and to utilize a signal which varies as some function of the clutch apply pressure in a control system regulating the clutch operation. It is also desirable in many cases to provide an indication of the temperature of the transmission oil or clutch apply fluid. Generally this has been done by providing an additional, separate sensor positioned in the appropriate location to provide the requisite temperature indication.
The space allotted for the provision and mounting of the various sensors is very limited in many modern compact, transaxle combinations. It is therefore a primary consideration of the present invention to provide an effective means for indicating both the pressure and the temperature of the fluid in the clutch control line and/or the transmission, in a minimum physical volume. A corollary consideration is to provide such an arrangement in which the temperature and pressure signals are very accurate over the operating range of the system being controlled. Another important consideration is the provision of such a sensing arrangement in which the sensor itself can be easily replaced, without the necessity of recalibrating the associated control system.